110 



THE SKELETON OF THE HORSE 



Development. — The fibular tarsal bone has two centers of ossification, one for 

 the main mass and the other for the tuber calcis; the latter fuses with the rest of the 

 bone at about three years of age. The first and second tarsals have separate cen- 

 ters, but fusion usually occurs before birth. Each of the other bones ossifies from 

 a single center. 



Tuberosity *- 



Ridges for 

 attachment 

 of middle in- 

 ferior sesa- 

 moid ligament 



hnprint for 

 tendon of _ 

 superficial 

 flexor 

 Condyle ■■' 

 Transverse 

 prominence - ~ 



Condyle 



Proximal 

 border. 



Flexor 

 surface ~ 

 Wing 



Volar 



graori 



Vdni- 

 f Oram I n 

 Semilu- 

 nar crest 



Flexor 

 surface 



^Proximal 

 sesanwids 



— s-iSZt 4 Phalanx I 



.^' 



^, Phalanx II 



Third 

 sesamoid 

 or navic- 

 ■ ular bone 





Proximal ^_ _ Os 

 sesamoids 



Phalanx I 



Phalanx II 



Third sesa- 

 moid or na- 

 vicular bone 



Foramen 

 I N^otch 



! / 



' Phalanx III Phalanx Illy 



Fig. 86. — Digit.\l Bones of Fore Limb of Horse, 

 Volar Aspect. 



Fig. 87 



-Digital Bones of Hind Limb of Horse, 

 Volar Aspect. 



THE METATARSUS 



The metatarsal bones (Ossa mctatarsalia), three in number, have the same 

 general arrangement as the metacarpal bones, but present some important differ- 

 ences. Their direction is slightly oblique, downward and a little forward 



The large or third metatarsal bone is about one-sixth longer than the corre- 

 sponding metacarpal; in an animal of medium size the difference is about two inches. 

 The shaft is more cylindrical, and is almost circular on cross-section, except in its 

 lower part. At the upper part of its external surface there is a groove, which is 

 directed obliquely downward and backward, and is continued by the furrow formed 

 by the apposition of the external metatarsal bone; it indicates the course of the 

 great metatarsal artery. A faint impression in a similar place on the inner side 



